What is Metastasis?

Approved by the Cancer.Net Editorial Board, 01/2016

Metastasis is the medical term for cancer that spreads to a different part of the body from where it started. When this happens, doctors say the cancer has “metastasized.” Other names for metastasis are “metastatic cancer” and “stage 4 cancer.” Sometimes the term “advanced cancer” also describes metastatic disease, but this isn’t always true. For instance, “locally advanced” cancer is not the same as metastatic cancer. It describes cancer that has spread to nearby tissues or lymph nodes but not throughout the body.

This page gives you basic information about metastasis, including how it happens and treatment options.

How metastases develop

Metastases (the plural form of metastasis) most commonly develop when cancer cells break away from the main tumor and enter the bloodstream or lymphatic system. These systems carry fluids around the body. This means that the cancer cells can travel far from the original tumor and form new tumors when they settle and grow in a different part of the body. Metastases can also sometimes develop when cancer cells from the main tumor, typically in the abdominal (belly) cavity, break off and directly “seed” other areas within the abdominal cavity.

Any type of cancer can metastasize (spread). Whether this happens depends on several factors. These include:

  • The type of cancer

  • How aggressive (fast growing) it is

  • How long you have it before treatment

  • Other factors

Where metastases develop

Metastasis to the bones, brain, liver, lymph nodes, and lungs is common. Cancer cells can also metastasize to the pleural space (the lining around the lungs) or the abdominal cavity. This may cause excess fluid buildup in these areas (called malignant pleural effusions and malignant ascites). Multiple tiny metastases in the abdominal cavity are referred to as peritoneal carcinomatosis. Less frequently, cancer can also spread to the skin, muscle, or other organs throughout the body.

Some cancers tend to spread to certain parts of the body. For example:

  • Breast cancer tends to spread to the bones, liver, lungs, chest wall, and brain.

  • Lung cancer tends to spread to the brain, bones, liver, and adrenal glands.

  • Prostate cancer tends to spread to the bones.

  • Colon and rectal cancers tend to spread to the liver and lungs.

Is a metastasis the same type of cancer as before?

Doctors give a metastasis the same name as the original cancer. So a breast cancer that spreads to the liver, for example, is referred to as “metastatic breast cancer,” not liver cancer. This is because the cancer started in breast cancer cells. However, even though the tumors in each of these different locations represent breast cancer, doctors are learning more about how metastases may differ from the primary (original) tumor at the molecular and genetic level. This is referred to as intrapatient tumor heterogeneity.

How do doctors diagnose metastasis?

If you already had cancer treatment for non-metastatic cancer, you probably have a follow-up care plan. You see your doctor for regular examinations and tests. Part of the reason for those follow-up tests is to look for any evidence of metastases.

Alternatively, some individuals already have metastases at the time of their original cancer diagnosis, and they are found during the initial staging evaluation.

Cancer may or may not cause symptoms, such as pain or shortness of breath. Sometimes these symptoms lead a doctor to perform the necessary tests to diagnose the presence of metastases.

How do doctors treat metastasis?

Treatment depends on:

  • The original cancer and where it started

  • How much the cancer has spread and where it is located

  • Your age and health

  • Your personal treatment choices

Treatment for metastasis is often different from the treatment used for the original tumor. Most commonly, doctors might try one type of chemotherapy, and then switch to another when the first treatment no longer works. Or you might have a combination of treatments, such as chemotherapy, radiation, and/or even surgery to remove the metastases (see below).

Treatment options

The main treatments for metastasis include:

  • Treatment that affects your entire body – Doctors call this “systemic” therapy. It includes chemotherapy and other medications, such as targeted therapy, hormone therapy, and biologic treatment.

  • Treatment for the area with cancer–Doctors call this “local” therapy. It includes surgery, radiation therapy, and some other treatments.

When you choose treatment, talk with doctors who have experience treating a metastasis. Doctors can have different opinions on the best treatment plan. Learn more about getting a second opinion.

Does treatment cure metastatic cancer?

In some situations, metastatic cancer can be cured, but most commonly, treatment for metastases is not curative. But doctors can treat it to slow its growth and reduce symptoms. It is possible to live for many months or even years with certain types of cancer, even after the development of metastatic disease.

How well any treatment works depends on:

  • The type of cancer

  • How far the cancer has spread, and where it is located

  • How much cancer there is

  • If the cancer is growing quickly or slowly

  • The specific treatment

  • How the cancer responds to treatment

It is important to ask your doctor about the goals of treatment. These goals may change during your care, depending on whether the cancer responds to the treatment. It is also important to know that pain, nausea, and other side effects can be managed with the help of your health care team. This is called palliative care and should be a part of any treatment plan.

Treatment in clinical trials

Clinical trials offer treatments that are not yet available to the public. A trial might be the main treatment for metastases, or just one of the options. Just 3% to 5% of adults with cancer take part in clinical trials. The trial treatment may or may not help. But even if it does not, it gives researchers information that could help future patients. If you are interested in clinical trials, talk with your doctor and health care team.

When you live with metastatic cancer

When you live with cancer for many months or years, doctors often treat it like a chronic (long-term) illness. Like someone with another chronic illness, such as diabetes or heart failure, you need treatment. It’s important to follow your treatment plan so it works as well as possible. You also need support for the physical, emotional, and mental challenges of living with cancer.

More Information

Coping with Metastatic Cancer

Dealing with Cancer Recurrence

Advanced Cancer

Additional Resources

National Cancer Institute: Metastatic Cancer

American Cancer Society: Advanced Cancer

ASCO answers; When Cancer Spreads to the Brain

Download ASCO's free 1-page fact sheets on When Cancer Spreads to the Brain and When Cancer Spreads to the Bone. These printable PDFs provide an introduction to metastasis, including symptoms, treatment options, terms to know, and questions to ask the doctor. Order printed copies of both fact sheets from the ASCO University Bookstore.